Spinal cord, Spinal nerve & ANS Flashcards
Gray matter
-Collection of cell bodies adn unmyelinated axons and dendrites within the CNS
White matter-
-Myelinated axons and dendrites within the CNS
3 spinal meninges
- Dura mater
- —epidural space
- Arachnoid mater
- —subarchnoid space
- —–lumbar cister
- Pia mater
- —denticulate ligaments
- —filum terminale
Filum Terminale
-anchors cord inferiorly
How many pairs of spinal nerves?
31
Nerve-
-collection of neuronal (cell) processes, dendrites and axons, surrounded by connective tissues coverings
Dermatomes
- Sensory nerve distribution
- none on head–start at neck
Myotomes
-Motor nerve distribution
Neuron
-basic functional unit of the nervous system
Synapse
-functional communication between a series of neurons
Afferent
- neuron which sends impulses towards the CNS
- Sensory
Efferent
- Neuron which sends impulses away from the CNS
- Motor
Somatic
-Pertaining to the body, typically the body wall
Visceral (Splanchic)
-pertaining to the gut, viscera
Ganglion
-collection of cell bodies (nuclei) outside of the CNS
Rootlets
- Located within the meninges (subarachnoid space) of the spinal cord
- Dorsal (Sensory)
- Ventral (Motor)
Roots
- Rootlets combine and are surrounded in connective tissue sheath
- Dorsal (Sensory)
- Ventral (Motor)
Dorsal Root Ganglion
- Collection of sensory cell bodies outside of the CNS
- Lies within the intervertebral foramen
Dorsal root
-Sensory
Ventral root
-Motor
Spinal nerve
-mixed
Dorsal primary ramus
mixed with sensory and motor
- -synovial joints of vertebral column
- -deep muscles of the back
- -overlying skin of the back
Conscious nervous system
- General sensory
- —General somatic afferent
- Somatic motor
- —General somatic efferent
Unconscious nervous system
- Visceral Sensory
- —General Visceral Afferent
- Visceral Motor
- —General Visceral Efferent
Autonomic Nervous system
- Sympathetic (Thoracolumbar)
- Parasympathetic (Craniosacral)
Sympathetic
-Fight or flight
Parasympathetic
-rest and digest
Pre-synaptic (ganglionic) neuron
-located within the CNS
Post-synaptic (ganglionic) neuron
-located with the periphery
2 spinal enlargements
-cervical
—-upper limb innervation-spinal level-C4-T1
Lumberosacral:
—-lower limb innvervation-spinal level-L1-S3
Cauda equina
- location-lumbar cistern (sub-arch space-
- dorsal and ventral rootlets located with the subarchnoid space are directed towards the intervertebral foramina to exit the vertebral column
- includes the conus medullaris and filum terminale
Dura mater
-epidural space
Arachnoid mater
- subarchnoid space
- —lumbar cistern
Pia mater
- denticulate ligaments
- filum terminale
Denticulate ligaments
-located within the pia mater with 21 attachments per side which attach to arachnoid and pia mater to stablize vertebral column
Ventral primay ramus
- the remaining areas of the trunk, upper & lower limbs
- rearranged into the nerve plexuses
- –cervical plexus (C1-C50, brachial plexus (C5-T2), intercostal nerves (T1-T11), lumbar plexus (T12-L4), sacral plexus (L4-S5), coccygeal nerve (Co)
Cervical plexus
-C1-C5
Brachial plexus
-C5-T2
Intercostal nerves
-T1-T11
Lumbar plexus
-T12-L4
Sacral plexus
-L4-S5
Coccygeal nerves
-coccy
Components of typical spinal nerve
- general sensory (general somatic afferent)
- somatic motor (general somatic efferent)
- visceral sensory (general visceral afferent)
- visceral motor (general visceral efferent)
- connective tissue coverings
- vasa nervorum
Vasa nervorum
-blood vessels
Connective tissue coverings
- endoneurium
- perineurium
- epineurium
Visceral motor
- general visceral efferent
- -transmits impulses from CNS to smooth muscle and glandular tissue (ANS)
Visceral sensory
- general visceral afferent
- -transmits reflex pain from viscera, glands, mucous membranes and blood vessels to spinal cord
Somatic motor
- general somatic efferent
- -transmits impulses from spinal cord to skeletal muscle
General sensory
- general somatic afferent
- -transmits pain, temp, touch, pressure, proprioception to spinal cord
2 divisions of ANS
- sympathetic (thoracolumbar)-fight or flight
- parasympathetic (craniosacral)-feed and assimilate
Parasympathetic
- energy conserving (feed and assimilate)
- neurotransmitter-acetylcholine
- sites of presynaptic cell bodies
- -1. Cranial nerves III, VII, IX, X
- -2. Sacral segments 2-4
- sites of postsynaptic cell bodies
- -1. within the wall of the organ it innervates
Sympathetic
- energy-expending system (flight or fight)
- neurotransmitter-norepinephrine
- cell bodies of presynaptic (preganglionic) neurons are located in INTERMEDIOLATERAL CELL COLUMN of the spinal cord between the T1-L2/L3–also termed the LATERAL HORN
- cells bodies of postsynaptic
Courses of presynaptic sympathetic fibers
- enter the spinal nerve via the ventral root
- enter the sympathetic trunk (chain) via white rami communicantes
- they can choose to synapse immediately
- can choose to ascend or descend the sympathetic trunk to synapse
- they can choose to pass through the sympathetic trunk without synapsing
- —-splanchnic nerves to prevertebral ganglion
Course of postsynaptic sympathetic fibers
- run through gray rami communicantes entering the spinal nerve
- Head: follow branches of the carotid artery
- splanchnic nerves follow branches of the abdominal aorta
- visceral afferent (sensory) neurons run with the sympathetic divison of the ANS in a dermatomal pattern
